The primary objective of this trial is to evaluate the safety and tolerability of multiple intravenous infusions and repeated courses (maximum of two) of ORTHOCLONE OKTcdr4a in patients with active rheumatoid arthritis. This new agent is a monoclonal antibody which is directed against a portion of the human T lymphocyte CD4 molecule. This is a humanized murine antibody, which means that the constant region of the human immunoglobulin molecule has been spliced with the murine CDR variable region so that the amount of mouse sequence is reduced to 8% of the total sequence while specificity for CD4 + T cells is retained. The trial design will test a dosing range of a total of 150 mg and 500 mg ORTHOCOLONE per course of therapy. Secondary objectives will include collection of data to assess the pharmacokinetics, clinical activity, biologic activity and immunologic activity including the generation of anti-ORTHOCLONE antibodies.